Among other advantages, removing the crown of a pipe weld so that the weld is flush with the pipes being welded permits ultrasonic inspection of entire weld volume with the ultrasonic beam angle precisely known and without the need to use full vee-path inspection techniques. The chief application of such pipe weld crown removal is in the surface preparation of welds for ultrasonic testing during in-service inspection.
A number of different prior art devices have been developed for cutting and grinding pipes and other cylindrical surfaces. Some examples of such devices are those disclosed in the following patents: U.S. Pat. Nos. 2,693,066 (Berstecher); 3,432,971 (Conti); 2,455,762 (Hall); 2,696,065 (Harnes); and 3,149,440 (Maguire). Briefly considering these patents, the Berstecher patent discloses a portable grinder for a workpiece having cylindrical surfaces such as those of a roll used in paper making. The device encircles the workpiece and includes a plurality of planetary grinding wheels which are carried by ring members and which revolve around the workpiece as well as rotate about the individual axes. The grinding wheels are also movable radially inwardly and outwardly relative to the workpiece by means of a mechanism including a hydraulic piston and a swing link. A system of pulleys and V-belts are used to drive the grinding wheels from a single input drive shaft. The Conti patent discloses a wire grinding machine wherein a pair of grinding wheels are arranged symmetrically with respect to the axis of rotation of, and rotate with, a drum which supports the wheels. A drive assembly mounted in the drum provides for rotation of the wheels about their respective axes. The Hall patent discloses a pipe grinder for grinding ends of pipe roughened by a cutting torch. The grinder is affixed to the open end of a pipe and includes a slidable frame that slides relative to a fixed frame. The Harmes patent discloses a pipe cutter including an abrasive disc which rotates about the pipe to be cut. The Maguire patent discloses a machine for cutting and grinding wherein the associated cutting and grinding tools thereof undergo a planetary and axial movement.